1. Field
The following description relates to an integrated semiconductor device with a hybrid transistor, a high voltage transistor, and a low voltage transistor. The following description also relates to a method for manufacturing such an integrated semiconductor device.
2. Description of Related Art
An integrated semiconductor device with a hybrid transistor, a high voltage transistor and a low voltage transistor is quite useful for several device functions. For example, the high and low transistors are generally used for analog and mixed-signal applications. A hybrid transistor is preferred for operation as an amplifying or switching device. A lateral diffusion MOS (LDMOS), a vertical diffusion MOS (VDMOS), and a trench VDMOS (Trench VDMOS) are examples of asymmetrical power metal-oxide-semiconductor field-effect transistors (MOSFETs). The structures of a source and a drain formed in the hybrid transistor are different from each other. Because the hybrid transistor has a rapid speed of operation compared to a high voltage transistor of the same size, the hybrid transistor is often used as a switching device. The switching device performs the role of controlling electric power such as by switching to power standby status, switching to turn a display off, and switching to a save mode when a battery level is at a below average level.
The hybrid transistor is made to have an integrated structure by using the same mask used for manufacturing of an LV/HV device. When a separate mask is used for a hybrid transistor, inefficiency in terms of overall costs happens because of increase in manufacturing costs. However, when the hybrid transistor is manufactured by an approach based on the integration with a HV/LV device, the low on-resistance (Low Ron) and low leakage current characteristics required for a hybrid transistor deteriorate.